Note: Descriptions are shown in the official language in which they were submitted.
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This lnvention relates to an apparatus for feeding
wire at great distances for the purpose of welding in protective
atmospllerc, the drive being ef~ected by a DC motor operating
in collditioll of interrupted current.
A known wire-feeding apparatus comprises a wire-
feeding mechanism, a thyristor stage, a generator for ignition
pulses and a speed stabilizer.
The drawbacks of this apparatus lie in that, the
in-line connection of the different mechanisms results in a complex
system for automatic regulation, featured by unstable operation.
Moreover, the regulation of the power supplied to the motors is
a function only of the current of the first feeding mechanism and
requires, therefore, a higher coefficient of amplification in each
of the following regulators, this being also a cause for unstable
operation. The reduction of this coefficient would lead to a
different load distribution at different speeds, since the func-
tional connection bet~een the different regulators does not depend
on the speed. Finally, the use of a regulator for each wire-feeding
mechanism makes the system complex and expensive and reduces its
overall reliability.
It is, therefore, a general object of this invention
to provide an apparatus for feeding wire at great distances,
which is featured by simplified layout, as well as to achieve a
high quality of regulation, thus achieving stable operation at
equal loading of the different motors at all speeds, without
mechanical slippage, and that at a higher reliability,
This object is achieved by connecting the output
of the generator of ignition pulses of the first wire-feeding
device by means of a synchronization bus to the inputs of the
generators of pulses of the second and the next wire-feeding
devices. For a more stable operation and for an equal loading of
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the different motors, it is suitable to connect the inputs of the
generators of ignition pulses of the second and the next wire-
Eeeding devices to the outputs of the formers of synchronizing
pulses, the other inputs oE which are connected to one of the supply
buses. At nominal w~rking conditions, the formers of synchronizing
pulses comprise in their input a resistor, which is connected to
one of the supply buses.
For improved operation at higher currents, the
formers of synchronizing pulses can comprise in their input a
current transformer, the primary winding of which is connected to
one of the supply buses.
The advantages of the invention lie in that the
phase of triggering the thyristor in the regulator of the first
device depends on load, as well as on the speed; thus there is
produced a combined connection between the different regulators
by current, as well as by speed. Moreover, the operation of the
motor in condition of interrupted current results in dropping
characteristics of the electric drive of the second and the next
mechanisms, and this prevents mechanical slippage, and by means
of variation of the speed above or below the speed of the first
motor there are provided conditions for such a variation of the
lengths of electrode wire between the different mechanisms which
equalizes the loading of the different motors. After equalizing
the loading of the different wire-feeding mechanisms, there is
equalized the speed of the next-following mechanisms with that
of the first wire-feeding device, which influences decisively the
quality of welding. The lack of speed stabilizers or of following
systems in the second and the next wire-feeding devices results
in more stable operation since otherwise there would be obtained
a sysbem for automatic regulation of higher level, composed of
different closed systems for automatic regulation, connected by
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complex connections - variable mechanical connection and electric
feedbacks. The lack of speed stabilizers or following systems in
the second and the next devices results in a simplified and cheaper
control system and to an increase of the overall reliability.
It is possible to connect two, as well as three or
more wire-feeding devices by the described method.
For a better understanding of the invention, reference
should be made to the accompanying drawings in which there is il-
lustrated a preferred embodiment of the invention. In the drawings:
Figure 1 shows three in-line connected wire-feeding
devices with a special bus for synchronization;
Figure 2 shows three in-line connected wire-feeding
devices with synchronization of the thyristor stages in accordance
to the start of the current pulses of the first motor;
Figures 3 and 4 show the connection of the formers
of synchronizing pulses;
Figures S and 6 show the characteristics of the
first and the next wire-feeding devices.
It is seen in the drawings, that the first wire-
feeding device 1 is connected to the next wire-feeding devices 2
by means of the mechanical connection 3, which is the electrode
wire itself, coming from reel 4, and two electrical connections
S and 6, which are the supply buses. Moreover, the devices in
Fig. 1 are connected also to a synchronization bus 7. Each wire-
feeding device 1 or 2 comprises one wire-feeding mechanism 8, a
thyristor stage 9 and a generator of ignition pulses 10. The gene-
rator of ignition pulses 10 has an input 12 for synchronizing
pulses, an output 13 for ignition pulses, and an output 14 for
synchronizing pulses. The latter output is necessary only in one
case in the first wire-feeding device 1, as seen in Fig. 1. The
first wire-feeding device 1 comprises also a speed stabilizer 15,
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the input of which is connected to the wire-feeding mechanism 8,
while its output is connected to the input 16 of the generator
of ignition pulses 10. The output 13 of the generator of ignition
~ulses 10 of each wirefeeding device 1 or 2 is connected to the
thyristor stage 9, and the latter - to the wire-feeding mechanism
8 supplying its motor. The inputs 12 of the generators of igni-
tion pulses 10 of the second and the next wire-feeding devices 2
are connected by means of the synchronizing bus 7 to the synchroniz-
ing output 14 of the generator of ignition pulses 10 of the first
wire-feeding device 1 or to the output of the former of synchroniz-
ing pulses 17, through which one of the supply buses 5 or 6 passes.
The formers of synchronizing pulses I7 can be provided
in their input with a resistor 18, connected in-series to the supply
bus 5 or 6, and in this case they will react to the drop of voltage
in this resistor. The formers of synchronizing pulses 17 can be
provided with a current transformer 19l ins~tead of with a resistor.
The speed of the wire-feeding mechanism 8 of the
first wire-feeding device 1, and thus also the speed of the elec-
trode wire in the area of welding, are stabilized by the speed
stabili~er 15. By means of synchronization bus 7 or supply bus 5
or 6 and the former of synchronizing pulses 17, all generators of
ignition pulses 10 are excited simultaneouslyî they produce ignition
pulses and trigger simultaneously the thyristors of the thyristor
stages 9. The electric time-constant of the motors is such, that
they operate in condition of interrupted current. This, as well
as the lack of stabilizers for the speed, provides for dropping
characteristics of the motors of the wire-feeding mechanisms 8
of the second and the next wire-feeding devices 2.
Let the preset speed be ~A. Then the working A of
the first wire-feeding device 1 will be somewhere along the hori-
zontal line with ordinate ~A. It is assumed, that the first wire-
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feeding device 1 has pulled and stretched the greatest portion ofthe wire between itself and the second wire-feeding device 2.
Then the latter is loaded less and its working point B lies on that
characteristics which passes through point A. Its speed is higher
and it starts to apply gradually a pushing force on an ever growing
portion of wire in tront, and thus it is loaded more and more and
unloads the first wire-feeding device 1, until both devices are
set in working point A' where they are equally loaded. On the
contrary, if the second wire-feeding device 2 is more loaded and
its working point is C, then it moves at lower speed and the first
wire-feeding device 1, moving at higher speed, pulls an ever
growing portion of the wire between itself and the second wire-
feeding device 2 and it is thus loaded more and more while unloading
the second wire-feeding device 2, until both are set in working
point A. The operation of the next-following wire-feeding devices,
which have the same characteristics as the second wire-feeding
device 2, is analogue.
All thyristor stages 9, generators of ignition pulses
10 and speed stabilizers 15 of the first wire-feeding device 1 can
be disposed in the last most closely to the reel 4, wire-feeding
device or in the welding current source. Then their connection
is effected according to the layout illustrated in Fig. 1.
A delay for additional correction can be effected
in the generator of ignition pulses 10 of the first wire-feeding
device - output 14 or in the former of synchronizing pulses 17, or
in any of the generators of ignition pulses 10 of the second and
the next wire-feeding devices 2.
